make: added CPU_MODEL & TERMFLAGS to Makefile.vars

- added CPU_MODEL variable
- added TERMFLAGS variable
- fixed a little style (dots on the end of comments)
Merge pull request #1591 from haukepetersen/fix_make_vars

make: added CPU_MODEL & TERMFLAGS to Makefile.vars
board/pca10000: added make targets

- added `reset` target
- added `debug` target
- added `debug-server` target
- adjusted `flash` target